AI/Copilot panes render blank white (GPU compositing) while output streams fine - AMD/Win11, tmax 1.12.1

[kremertal]

What happens

For the last few days, Copilot CLI / AI panes render as a blank white area — no output paints at all. The agent is actually running fine underneath; it's purely a rendering problem.

The pane background should be dark (my theme bg is #1e1e2e), but the empty area paints white, which looks like an unpainted Electron/xterm surface rather than the terminal just being empty.

Why I think it's a renderer / GPU-compositing issue (not the CLI)

From tmax-diag.log while the screen was blank:

• pty:data bytes are streaming normally the whole time
• tmax logs renderer:ai-link-call ... "status":"executingTool" — so it knows the agent is working
• No errors / warnings / gpu / webgl / crash lines anywhere in the log

So data is arriving, tmax knows it's working, but nothing gets drawn. White-over-dark-theme = the canvas/compositor surface isn't painting.

What I already tried

• Confirmed I'm on the latest 1.12.1 (auto-updated) — still happens, so it's not a stale build.

Environment

• tmax: 1.12.1
• OS: Windows 11 Enterprise, build 10.0.26200.0
• GPU: AMD Radeon(TM) Graphics, driver 32.0.22024.17002 (2026-05-04)
• Shell: PowerShell 7 (pwsh)
• Session type: Copilot CLI (also seen with the GitHub FLOAT panel open)
• Config of note: backgroundOpacity: 0.8, backgroundMaterial: none

Suspected cause

AMD + Electron GPU compositing blank-canvas glitch, likely triggered by a recent GPU driver update + stale GPU cache. Clearing GPUCache / DawnGraphiteCache / DawnWebGPUCache and/or launching with --disable-gpu are the usual mitigations — filing so the app can handle/detect this more gracefully (e.g. auto-recover a lost GPU context, or a built-in "reset renderer" action).

Repro

1. Run a Copilot CLI session in a tmax pane (AMD GPU, Win11).
2. Let it work for a while / reopen after a driver update.
3. Pane goes blank white while output is still streaming in the diag log.